Reservoir coring



Dec. 1, 1959 J. E. ORTLOFF 2,915,284 RESERVOIR comm;

Filed Jan. 14,1955 a Shee ts-Sheet 1 coRE BARREL 7 CORE l4 SLEEVEPOSITION j DURING CORING OPERATION DRILL STEM- j 40 TUBE/ l4 I I 4SIVEEVE TUBINGGPORT CORE VE BALL, 27 SHARP CHECK A EDGE BALL VALVE eASSEMBLY 2 SPRING .5 a a F j \IQ alT lo SEALS-30 SEALING AMS 26 FIG. I vv REGIPROCATING 2; AIR MOTOR 3| '3 RECIPROOATING ROD I /I4 l4 SUB l8 2L4 7 SECTION 3-3 4,] FIG. 3

FIG. 2

John E.Ortloff Inventor By 2 z Afiorney J. E. ORTLOFF RESERVOIR 00am:

Filed Jan. 14, 1955 3 Shgets-Sheet 3 I CORE BARREL CORE TUBING 6. PORTDRILL STEM Av E ,8

O l 7 M4 2 m2 RECIPROCATING AIR MOTOR .RECIPROCATING RAM Inventor JohnE. Ortloff Attorney United States Patent 2,915,234 RESERVOIR coRusG John-E Ortloif, Tulsa, Okla., assignor, by mesne assign- :ments, .;toJersey'lroduction Research Company Application January 14, 1955, SerialNo. 48,, 1,837

1-3 Claims. (Cl. 25-5-14 It particular-1y relates to a method andapparatus ice ing liquid in a hole still constitutes anundesirablefeature' when sampling a reservoir of the-type describedabove for the reason that the "hydrostatic pressure and the core samplemay be obtained without employing drill- 1 ing mud, the presence ofwhich has been found on occa sion to seriously contaminate such samples.The method and apparatus are further particularly characterized by thefact (1) that the core sample may be continuously maintained undersubstantially ambient formation conditions, and (2) that it may besealed off to prevent the loss of any fluids therefrom.

A serious and important problem that confronts the petroleum producingindustry at the present time is one of obtaining reliable samples ofpetroliferous formations that lie beneath the surface of the earth. Theproblem has become one of particular importance in view of the everincreasing use of secondary recovery methods for obtaining additionaloil from subterranean oil reservoirs that have ceased primaryproduction. It is essential, before initiating a secondary recoveryprocedure in any such reservoir,'to have as much information as possibleabout the structure, the fluid content, the pore volume, thepermeability, etc. of the formation. Such information is extremelyvaluable in determining whether the formation is susceptible tosuccessful exploitation using secondary recovery techniques and justwhich techniques should preferentially be utilized.

In line with the growing emphasis on secondary recovery programs, manypetroleum producers are conducting extensive analyses of old reservoirsand fields that have in years past lost their reservoir pressure andbeen abandoned. In an effort to evaluate these old reservoirs and fieldsand in order to determine whether a secondary recovery procedure can besuccessfully applied to them, the producers are conducting extensivesampling prog rams. One'sampling technique has been to drill and samplethe bottoms or side walls of old wells that were originally producingwells associated with a reservoir or field. It has been determined,however, that the samples derived by this technique are quite inaccurateand not representative of the field or reservoir as a whole.Accordingly, it has become more and more the established practice todrill entirely new holes from the earths surface down to a petroliferousformation and to obtain samples of the formation directly from these newholes. Conventional drilling and coring methods such as rotary and cabletool have been employed for this purpose. In

all of these types of drilling, however, it is necessary to use at leasta small amount of drilling mud, water or other drilling fluid in thebottom of the hole in order to properly lubricate the bit and to disposeof the cuttings; and it is therefore conventional to have at least aboutto 50 feet of water or other drilling fluid within a hole.

The presence of the rilling mud, water or other drillwetting eflects ofeven this small amount of liquidare considered .to seriously interferewith the reliability of the samples that areobtained. Itis accordinglyan obi: ject of the present invention to provide an apparatus and methodfor obtaining reservoir core campleswherein the samplesneed not besubjected to a drilling liquid of any kind. It is a further object.oftheinvention to provide means for coring aformat'ion in suoha mannerthat the core sample suffers a very limited exposure to any materialthat could conceivably be a source of contamina tion. It is a particularobject of the invention tov pro ide means for isolating a core samplewithin thecoring apparatus so that connate liquids are retained with;the

sample. it is further a particular object of the invention to provide acoring method and, apparatus'wherein the These objectives are realizedin accordance with the invention by utilizing ,a coring apparatus andprocedure which employ a conventional type of coring bit. 1 As the bitpenetrates the formation, the resulting core sample is forced interiorlyof the coring apparatus and into a posi= tion within a core barrel. Whenthe desired amount of core sample has been forced within the barrel, theapparatus is raised and the core sample is parted at a point verticallywithin the coring apparatus and above the coring bit as will beexplained in greater detail later in this description.- At this pointthe entrance to the core barrel is closed so as to entrap the sample andits connate fluids within the barrel, and preferablyso as to maintainthe sample and fluids under ambient formation conditions;

At this point the apparatus and its encased samplernay be withdrawn tothe surface of the earthandexamined or analyzed as desired, Theapparatus and procedure of the present invention may be employed alongwith conventional drilling means; but in a preferred embodiment of. theinvention, the:ap+ paratus and procedure are utilized inconjunction withair or any other suitable gasiform materialas thedrilling fluid.Further, the invention may make use of rotary-"or percussion-typedrilling apparatus, although the lattertype of apparatus is employed in'a preferred embodiment of the invention. Thus, in a particularlypreferred embodiment of the invention, a pneumatically powered,percusslon-typepower source is employed to drive a coring bit; and-airjsutilized as. a drilling fluid to cool the bit and to remove cuttingsfrom the vicinity of the bit. This embodiment of the invention as wellas the broad concept of the invention is best understood 'by referenceto the attached figures where: p

Fig. .1 is a view in vertical cross-section'of a portion of oneembodiment of the inventiom;

F g. 2 is a view in vertical cross-section of another portion oftheembodiment of' Fig. 1 which is a continuat on of the portion in Fig. .1and which is ordinarily positioned vertically above'the portionillustratedin Fig. 1. Fig. 31s a view taken along the lines 33"of Fig.1-. Fig. 4 is a view in vertical or ss section of another embodiment ofthe invention. i

- Fig. 5 is a vview in vertical cross section of a portion of v oneembodiment of the invention illustrating theposition sealed within thebarrel.

Turning to the figures, it will be observed that the apparatus thereinincludes a drill stem 4, an air motor 5, a sub 6, a core barrel 7, acore catcher 9, a coring bit 10, and a reciprocating rod 11 connectingthe subto the motor 5. The figures further illustrate a sleeve valveassembly 12, a pair of sealing rams 13, conduits 14, check valveassemblies 15 and a core sample 16.

In examining the apparatus of Figs. 1-3 and Figs. 57, it will be assumedthat this apparatus is employed at the bottom of a bore hole with thedrill bit directly above and contacting the bottom of the hole. It willfurther be assumed that the widest portion of the apparatus, normallythe bit itself, is sized so as to move freely and centrally within thebore hole. Thus, there exists an annular space that lies between theouter surface of the overall apparatus above the bit and the inner wallsurface of the bore hole and which extends substantially the entirelength of the bore hole.

It will further be assumed that the apparatus, as illustrated in Figs.1, 2 and 3, is depicted in that phase of a coring operation wherein asample has been drilled, forced within the core barrel, parted from theformation, and

During the actual coring procedure, the ball 17 is absent from theapparatus and the sleeve valve assembly 12 is in a raised verticalposition (indicated by the dotted lines) so as to seal off the upperentrances or ports to the conduits 14. The positions of the variouscomponents of the device during drilling operations are illustrated inFigs. 5, 6 and 7.

Having briefly identified the major components that are illustrated inthe figures, attention is now directed to a more detailed considerationand description of each one of these components. Taking first the bitmember 10, it will be noted that this member may be any conventionaltype of percussionor rotary-style coring bit. Both types are well knownin the art, and a detailed discussion of them therefore is notconsidered to be necessary in the present description.

The coring bit 10 is mounted and secured to the lower end of the submember 6 which extends vertically from the bit to the lower end of thereciprocating rod 11. As illustrated, sub member 6 has an annular typeconfiguration and houses the core barrel 7, the core catcher 9, the ballcheck assemblies 15 and the sealing rams 13. With particular referenceto the core barrel 7, it is necessary that the sub member 6 and the corebarrel be free to move relative to one another. Thus, in areciprocatingor percussion-type drilling apparatus such as isillustrated in the figures, it is necessary that the core barrel 7 befree to move vertically up and down within the sub member. Likewise,when the coring apparatus is of the rotary-type, it is necessary thatthe core barrel 7 be free to move rotationally With respect to thesubmember 6. Thus, during a coring operation, the core barrel 7 remainssubstantially stationary during movements of the sub member 6 and itsbit 10.

Since the apparatus in the figure is of the percussionorreciprocating-type, it will further be observed that the relativelengths of the core barrel 7 and the core barrel zone 18 within submember 6 must be of such dimensions that the core barrel remainsstationary within the zone 18 entirely unimpaired by the sub memberduring either stroke of the sub member. By observing this designconstruction, the core sample within the core barrel 7 is not subjectedto shocks or shearing forces that are occasioned by the movement of thesub member and the impacts of theibit 10.

In a lower portion of sub member 6vertically intermediate the bit 10 andthe lower end of the core barrel zone 18are provided recessed zones orram chambers 19 which are adapted to house the closure rams 13. In thefigures it will be seen that these zones are adapted tocompletelyreceive the ram members when the apparatus is actually engagedin a coring operation. During such time,each .ram is entirely containedwithin its respective ram chamber; and a free and continuous centralpassageway 20 is provided within the overall apparatus to enable thecore sample to move up within the apparatus and thence within the corebarrel 7 as particularly illustrated in Figs. 5, 6 and 7. On the otherhand, when the coring operation has been completed and a core sampletrapped within the core barrel 7, the rams are forced outward fromwithin their respective ram chambers; and the core barrel is sealed whenthe two rams come together, asparticularly illustrated in both Figure 1and Figure 3,. The actual step involved in driving the rams against oneanother is considered at greater length later in this. description.

Each sealing ram member 13 is preferably provided with a rubber or otherelastic and compressible surface 31, particularly where they engage oneanother in order to provide as good a sealing arrangement as possible.While rubber is a particularly preferred material for this purpose,other conventional gasket or sealing materials may be utilized at thispoint in the apparatus. Whatever material is employed, it may be bondedin any conventional, suitable manner to each one of the rams.

Still referring to the closure rams 13, it is necessary that they be ofa size such that they may be housed completely within the ram chambers19 during a, coring operation and also such that they may completelyseal off the passageway 29 when they are driven against one another. Inthe latter position, it is further necessary that each ram extendsufficiently within its respective ram chamber 19 so as to be amplysupported in the sealing position. Along this same line, it isparticularly desired that sealing means 30 be provided entirely aroundthe inner periphery of each ram chamber at a point near the entrance toits respective chamber. Suitable sealing means, for example, may berubber O-rings or other packing materials that are used in situationssimilar to the one illustrated in the figures. These seals 30 tend toprevent cuttings and other materials from entering the ram chambersduring a coring operation and also to prevent fluids or other materialsfrom entering or leaving the core barrel 7 and passageway 20. In otherwords, the seals 30 assist the rams in their function of completelyisolating a core sample 16 within the core barrel 7. The overalldimensions and configuration of the core barrel have been discussed inearlier paragraphs in this description. It may be added here that thecore barrel must be provided with a core catcher 9 and a core fracturingsection 21 which is adapted to separate the core sample from theformation and to perform the separation at a point vertically above thesealing rams 13. In this connection, a number of conventional corecatchers and core fracturing devices may be employed. It is particularlycontemplated that a sharp edge such as is illustrated in Fig. l is thebest type of core fracturing device to employ. In this type of device,the core catcher 9 loosely grips cores 16 and tends to ride upwardlywithin recess 40 during a coring operation. However, when coring iscompleted and the coring apparatus is lifted within the borehole, thecore catcher 9 tends to remain stationary relative to the remainingapparatus. The sharp-edged shoulder 21 causes the lower end of the corecatcher 9 to be thrust inwardly against the core and to break the coreat that point. A typical core catcher of this type is shown in theComposite Catalog of Oil Field Equipment; 20th Edition, 19544955, page1380. Drilling and Service, Inc., Dallas, Texas, is described as themanufacturer of the device. Page 1379 of the catalog shows the corecatcher in an assembled condition within a coring tool.

Pneumatic motor 5 may be any conventional form of reciprocating-typepneumatic motor which is of a size and power adapted to conduct a coringoperation. Such motors are well known in the art, and a detaileddiscussion of them is not considered to be necessary in thisdescription. There exists, for example, a large number of air-hammertype motors which are contemplated to be particularly well suited forthe purposes ofthis invention.

Still referring to motor 5, it will be noted thatthe motor, asillustrated, is arranged to impart a vertical reciprocating motion torod II which in turn imparts a similar motion to sub 6 and bit 10. Thus,the motor supplies the energy necessary to enable the bit to cut throughany given formation.

The effective stroke and frequency of the" motor 5 may vary over arather broad range consistent with known devices and conventionaldrilling techniques; It is contemplated, however, that" s'trokes'of from1 to 4 inches and frequencies of from 60 to 300 per minute are the bestto employ.

Air or other suitable gasiform fluid may be supplied to motor 5 througha suitable conduit system, preferably drill stem 4'. Drill stem 4extends from the air motor 5 to the top of the borehole where it may beconnected to a source of compressed air or other suitable gasiformfluid. The exhaust from the air motor may be directed into the annularspace between the drill stem and the bore hole and vented directly upthe bore hole to the surface of the earth.

At the lower portion of the drill stem and immediately above the airmotor 5 is positioned a sleeve valve assembly 12 which has been brieflyreferred to earlier in this description. As pointed out there, thesleeve valve portion 22 of this assembly is capable of taking one of twopositions depending upon the phase of the overall operation in which theapparatus is engaged. When the apparatus is actually in the process ofdrilling a core sample in a formation, sleeve valve 22 is verticallyabove its illustrated position of Fig. 2 and is in the position shown inFig. 6 so as to seal the upper entrances to the conduit 14 and therebyprevent air or other fluids from flowing into these conduits from thedrill stem 4. With the valve in this upper position, air then flowsdirectly down the drill stem 4 through the central passageway 23 in thesleeve valve portion 22 and thence through the inner open portion of thespring member 24 into the motor 5. Spring member 24 is of a size andstrength suflicient to maintain the sleeve valve portion 22 inthe'position where it seals off the conduit 14.

Sleeve valve portion 22 is provided with two valve seating surfaces-cnebeing its outer lateral surface which moves in a close fittingrelationship with the inner surface of the drill stem and the otherbeing a conical, seat 25 provided interiorly and near the bottomthereof. The latter valve seat-i.e., 25-i's closed by dropping a ball orother suitable plug down through the drill stem 4. The ball enters thecentral portion 23 of the valve assembly 12 and then comes to rest onthe valve seat 25, where it prevents air from entering the air motor 5;Air pressure within drill stem 4 then overcomes the strength of thespring member 24 and forces the sleeve valve member 22 verticallydownward, thereby exposing the entrance connections or ports to theconduits 14'. These conduits extend from the drill stern exteriorly ofthe coring apparatus to the interior portions" of the ram chambers 19.Thus, air entering the conduits 1'4 flows downwardly through theconduits and through the ball check valve assemblies 15 to the ramchambers 19 where it forces the rams outward from the chambers andagainst one another. It is apparent that the pressure employed to closethe sealing rams.13 may be entirely independent of the formationpressure and is isolated from and has no influence on the pressurewithin the core barrel 7. Thus, the amount of air pressure required ordesired to close the entrance to the core barrel is only indirectlygoverned or affected by the pressure within the barrel. Furthermore, thepressure exerted on the sealing rams 13 is continuously maintained byvirtue of the check valves within the check valve assemblies as well asthe seals surrounding the rams within the ram chambers.

It will be noted that the conduits 14 are provided with flexiblesections 26 to allow for the reciprocating motion ofthe overallapparatus: These flexible portions may be of a telescoping variety, butit is contemplated that flexible hose elements constitute the best formof apparatus to employ for this purpose.

Having described the structural features of the apparatus in Figs. 1-'3and Figs. 5-7, attention is now directed toward abriefexplanation of themanner in which the apparatus is operated. Figs. 5, 6 and 7 illustratethe position of the various components of the apparatus dur' ing-acoring operation. At the outset of this description, it will be assumedthat the apparatus has been positioned Within a bore holeand thatbit 10rests substantially at the bottom of the hole. It is further assumedthat the apparatusis intended to obtain a core sample of the formation'l-yingimmediately below the bottom of the bore hole.

With these assumptions in mind, it will be observed that sleeve valve22-is in its upper vertical position, thereby sealing off the entrancesto the conduits 14. At this point, compressed air is supplied from theearths surface through the drill stem 4 and thence through thepassageway 23 to the air motor 5. The influx of the compressed aircauses the motor 5 to impart a vertical reciprocating motion to rod 11which in turn imparts a similar motion to Sub 6 and bit 10. Bit 10thereby is repeatedly driven against the bottom of the bore hole topulverize a portion of the underlying formation and to cause a coresample of the formation to enter the space or passageway 20. The sealingrams 13, of course, are entirely enclosed with in the ram chambers 19,thereby permitting the core sample to enter freely within the interiorof the coring apparatus.

At this point it is necessary to indicate that it is preferred to directa stream of the air or other fluid from within the drill stem 4 (or fromthe earths surface) to a point near the bottom of the bore hole and inthe vicinity of the drill bit 10. This jetted stream of air serves tocool the bit and to carry any cuttings upwardly in the bore hole betweenthe wall of the borehole and the coring apparatus. Air velocities inthis annular space of about 3 to 10 ft. per second may be employed forthis purpose.-

As the coring operation progresses, the core sample within thepassageway 20' progresses upwardly until it eventually enters the corecatcher 9 and the core barrel '7; and when a sufficient sample has beenenclosed within the core barrel, the entire apparatus is lifted from thebottom of the bore hole. As the apparatus is lifted, it is apparent thatthe lower edge of the core barrel 7 eventually comes to rest on theshoulders 27 of the sub member 6'. As the apparatus is lifted beyondthis point,

the sharp-edged portion 21 causes the lower endof core catcher 9 to bedeflected inwardly against the core sample 16. Further lifting of theapparatus therefore causes the core sample to break at this point.

At this point the apparatus is lifted until it is clear of obstructionswithin the bore hole, and a ball 17 is then dropped Within the drillstem 4 until it comes to rest on the valve seat 25. With the ball inthis-position, additional air is forced down the drill stem 4 with theresult that the spring 24 is compressed and the sleeve valve 22 moved ina downward manner to expose the entrances to the conduits 14. Air thenflows directly through these conduits and into the ram chambers 19 whereit forces the sealing rams 13 from their chambers and into thepassageway 20. The air pressure in the ram chambers, furthermore, seatsthe two rams against one another; and the core sample 16 is therebycompletely sealed within the core barrel 7. It is important, of course,that the entire apparatus be lifted a sufficient distance after the coresample has been fractured so that the closure rams 13 are free to enterthe passageway 20 and not be obstructed in their movement by anyremaining portion of the core sample.

Having isolated the core barrel 7 by closure of the sealing rams 13, theentire apparatus may now be withdrawn from the bore hole with the coresample intact within the core barrel 7. After rams 13 are closed theparts of the device are then in positions illustrated in Figs. 1, 2 and3. The air pressure within the drill stem 4 may be reduced as desiredwithout fear of breaking the seal on the core barrel in View of the factthat the presure on the sealing rarns 13 is retained by the check valveassembly 15.

At this point it will be appreciated that the apparatus and procedurethat have been described in connection with Figs. 1-3 and Figs. 5-7represent merely one specific embodiment of the present invention.Actually, a number of modifications and variations may be resorted towithout departing from the spirit or the scope of the invention. Thus,it will be noted that the coring bit and assorted apparatus may be of atype that is actuated by rotary motion in place of a reciprocatingorpercussiontype motion. In this instance the rotary motion may besupplied by a turbine-type air motor in place of the reciprocating motor5, or it may be supplied at the earth's surface by means of aconventional rotary table or other suitable device. It is well known inthe art to employ rotary forms of coring apparatus, and only very minorchanges would have to be made in the apparatus of Figs. 1-3 in order toutilize a rotary power source. Thus, the core barrel 7 would have to beprovided with a conventional type of swivel connection to permit it toremain stationary with respect to the sub 6. Such a feature is a wellknown one in rotary forms of coring apparatus, and details of this typehave not accordingly been illustrated in any separate figures in thisdescription.

It will also be recognized that the sealing ram members 13 may be variedconsiderably in their configuration and design without departing fromthe scope of the invention. For example, it may be desirable on occasionto employ a single such ram member which is designed to be housed withinone side of the sub member 6 and to be driven across the passageway 20to the opposite side of the sub member thereby closing off the corebarrel in substantially the same manner as described earlier.Alternatively, it may be desirable to employ more than two such rammembers.

It will further be appreciated that the sealing ram members 13 may beclosed by employing means other than the compressed air apparatusillustrated in the figures. For example, it may be desirable to closethe rams by means of compressed springs or solenoids which are triggeredby suitable mechanical or electrical means from the earths surface. Itis contemplated, however, that the apparatus which is illustrated in theFigures 1-3 constitutes the best mode of carrying out the invention.

Figure 4 illustrates an apparatus embodiment of the invention whichincludes a number of the alternative features just described. Theapparatus in this figure includes a sub 6 and a core barrel 7, but inthis instance the sub and the core barrel are adapted for use with arotary drillin system. Core barrel 7 is mounted within the sub 6 bymeans of a suitable swivel 33; and the sub is threaded or otherwiseadapted at its upper end to be connected to a string of drill pipe, asuitable driving memher, or the like. Thus, inner barrel 7 is of acharacter to remain stationary with respect to the outer barrel or sub 6during a coring operation.

The apparatus in Figure 4 further differs from the apparatus of Figures1-3 in that it is provided with a single ram 13 which is normallyretained within chamber 19 during a corin, operation. Wound aroundrecess 19 is a solenoid coil 35 which upon energization is adapted tothrust ram 13 outwardly from its chamber 19 and across passageway 20into chamber 36. Electrical leads to the solenoid 35 are containedwithin conduit 34 which extends upwardly through the wall of sub 6. Theram member is preferably provided with a soft resilient material 31 asshown in order to effect a fluid-tight seal upon closure. Seals '31 arealso preferably provided to aid in this respect. q

A channel 32 is also provided in the wall of sub 6 to conduct drillingfluid from a drill string or other member or assembly above sub 6 to thebit 10. Thus, drilling fluid such as air may be passed down throughchannel 32 to the bit in order to remove drill cuttings as they areformed by the bit.

It will also be recognized that drilling fluids other than air may beused as desired. For example, conventional drilling liquids and drillingmuds may be employed, particularly where these fluids do not interfereseriously with the sampling operation. In this instance, the drillingfiuid system that is illustrated in the figures may be readily modifiedto accommodate these drilling liquids. Suitable gasiforrn fluids includethe chemically inert gases and other gases which are non-re active withthe core sample or its connate fluids and which do not interfere withanalyses, etc. performed on the core.

What is claimed is:

1. An apparatus for obtaining a core sample from a formation underlyingthe bottom of a bore hole which comprises a coring bit, a sub connectedto and vertically intermediate said coring bit and a drill stem, meansfor driving said bit against the bottom of the bore hole whereby a coresample is cut from the formation, a core barrel disposed within said submember and of a character to receive said core sample, means supportingsaid core barrel within said sub with free movement therein, r-amclosure members recessed within said sub member, means to force saidmembers against one another so as to seal off the entrance to said corebarrel, and fracturing means within said sub member positionedvertically above said ram closure members for fracturing and separatingthe core sample from the formation.

2. Apparatus for obtaining a core sample from a subterranean formationunderlying the bottom of a bore hole which comprises a coring bit, acore barrel above said coring bit, means for holding said core barrelabove said bit with said core barrel having free vertical movement withrespect to said bit, a passageway leading from said coring bit to saidcore barrel arranged to provide movement of the core sample from theformation into the core barrel, means for driving the coring bit throughthe formation and for forcing the core sample up within the core barrel,means for fracturing the core sample at a point vertically intermediatethe upper end of the core barrel and the bit, at least one retractableclosure member disposed adjacent said passageway vertically intermediatethe bit and said fracturing means, each said closure member being in theretracted position during a coring operation, and means for forcing eachsaid retractable closure member from its retracted position following acoring operation to close said passageway and to seal the fracturedsample within the core barrel under ambient formation conditions.

3. An apparatus for obtaining a core sample from a formation underlyingthe bottom of a bore hole which comprises in combination a drill stern,a coring bit mounted at the lower end of said drill stern, a core barrelpositioned intermediate the drill stem and the drill bit and adapted toreceive a core sample cut by the drill bit, means for supporting saidcore barrel above said bit with said core barrel having free verticalmotion with respect to said bit, means for driving said bit through saidformation whereby a core sample is forced within said core barrel, corecatcher means for holding the core sample within the core barrel,fracturing means for separating the core sample from the underlyingformation at a point within the coring apparatus, means for lifting thecoring apparatus vertically above the unsevered portion of theformation, retractable'closure members disposed within said coringapparatus and vertically below the fracturing means, said retractableclosure members being in the retracted position during a coringoperation whereby the core sample freely enters the core barrel, andmeans for driving the closure members from their retracted positionafter the coring apparatus has been lifted free of the unsevered portionof the formation whereby the core sample is sealed under substantiallyambient formation conditions.

4. An apparatus for obtaining a core sample from a formation underlyingthe bottom of a bore hole which comprises an annular type coring bit, asub connected to and positioned vertically above said coring bit, saidsub having internal shoulders at its lower end thereof and with the topof said sub enclosed, a drill string connected to and positionedvertically above said sub member, a core barrel within said hub membercommunicating with the central passageway in the coring bit, said corebarrel being of a greater diameter than 'the internal diameter of saidshoulder members, means for transmitting power via said drill string tosaid coring bit whereby a core sample is cut from the formation and isdriven upward and within the core barrel, fracturing means for partingthe core sample from the formation at a point vertically above andspaced from the coring bit, retractable closure members verticallyintermediate said bit and said fracture means arranged to seal thepassageway leading to the core barrel when the coring operation has beenterminated and when the apparatus has been lifted vertically above theremaining portion of the formation, and means for forcing said closuremembers from their retracted position.

5. An apparatus as defined in claim 4 in which the retractable closuremembers are rams adapted to be forced against one another.

6. In an apparatus for obtaining a core sample from the formationunderlying the bottom of a bore hole including a string of drill pipeand a core barrel and a coring bit secured to the lower end of the drillstring, the improvement which comprises means for supporting said corebarrel above said bit with said core barrel having free movement withrespect to said bit, fracturing means arranged to sever a core samplewithin said core barrel from the underlying formation, said fracturingmeans being positioned vertically above and spaced from the coring bit,retractable closure means positioned vertically intermediate said bitand the lower end of said severed core sample, means for lifting theentire apparatus vertically above the unsevered portion of theformation, and means for driving the retractable closure means from theretracted position and thereby sealing the core sample within the corebarrel.

7. An apparatus for obtaining a core sample from a formation underlyingthe bottom of a bore hole which comprises an annular type coring bit, asub connected to and vertically above said core bit, said sub beingenclosed at its upper end and having internal shoulders at its lowerend, a hollow drill stem connected to and vertically above said submember, means for driving said coring bit against the bottom of the borehole and for forcing the resulting core sample upward within said submember, a core barrel within said sub member adapted to receive saidcore sample through a passageway interconnecting the core barrel withthe opening in the coring bit, said core barrel having a larger externaldiameter than the diameter of said shoulder and having a smallerlongitudinal dimension than the longitudinal dimension between saidshoulder and said enclosure, core catcher means adapted to retain thecore sample within the core barrel, fracturing means within said submember arranged to separate the sample from the underlying formation ata point vertically above and spaced from the coring bit, retractable rammembers disposed within recessed chambers within said sub member, meansfor driving said ram members at least partially from said recessedchambers and thereby sealing the entrance to the core barrel.

8. An apparatus as defined in claim 7 in which the coring bit is of therotary type and swivel means are provided to support the core barrelfrom the sub member.

9. An apparatus as defined in claim 7 in which the coring bit is of thepercussion-type and the core barrel is slidably mounted within the submember.

10. in a coring apparatus including a sub, a coring bit attached to oneend of the sub, drive means attached to the opposite end of the sub, anda non-rotating corereceiving barrel mounted within the sub, theimprovement which comprises at least one retractable ram member mountedwithin said sub between said bit and said core barrel and adapted toseal a core within said apparatus, swivel means rotatably supportingsaid barrel from said sub, means to actuate each said ram from itsretracted position, and core-severing means adapted to sever a corewithin said core barrel.

11. in an apparatus for coring a subterranean formation including a subattachable at one end to a coring bit and at its opposite end tosuitable bit-driving means, the improvement which comprises acore-receiving barrel longitudinally slidably mounted within said huband adapted to receive a core cut by said bit, ram closure means mountedwithin said sub and adapted to seal the core opening through said bit,means to actuate said ram closure means, means limiting the longitudinalmovement of said core barrel within said sub, and core-severing meansadapted to sever a core within said core barrel.

12. In a coring apparatus including a coring bit and a barrel-like subinterposed between and connected at each end to said bit and a bitdriving means, the improvement which comprises a core barrel mountedwithin said sub in a manner to enable relative movement between said suband said barrel, said barrel being adapted to receive a core cut by saidbit, core severing means mounted adjacent the entrance to said corereceiving barrel, means limiting the longitudinal movement of said corebarrel within said sub, ram closure means retractably mounted withinsaid sub between said bit and said core severing means, means to actuatesaid ram closure means and said closure means being operable to seal thecore entryway into the apparatus.

13. In a rotary coring apparatus including a rotatable sub with a coringbit attached at one end thereof and a core-receiving barrel mountedwithin said sub, the improvement which comprises retractable ram meansmounted within said sub adjacent said bit and operable to seal the coreentryway within the sub, swivel means supporting said core receivingbarrel from said sub, means to actuate said ram means, and core severingmeans adjacent the entryway into the core barrel.

References Cited in the file of this patent v UNITED STATES PATENTS 1,112,49 8

